Abstract
Samples of commercial-purity titanium, with and without 10 vol.% TiC particulates, were thermally cycled about the allotropic transformation temperature of titanium. Thermal ratcheting was small for both unstressed materials. Upon application of an external uniaxial tensile stress, unreinforced titanium exhibited large strain increments, resulting from the biasing by the applied stress of the volume mismatch developed between grains during the transformation. Upon repeated cycling, a strain to fracture of 200% was reached, with a strain per cycle proportional to the external stress, in agreement with existing transformation-mismatch superplasticity models. The metal matrix composite displayed transformation-mismatch superplasticity as well, with a strain to fracture of 135% and a strain per cycle significantly higher than for unreinforced titanium. This novel enhancement of superplastic strain is modeled by considering the internal mismatch between the transforming matrix and the non-transforming particulates.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 1063-1076 |
| Number of pages | 14 |
| Journal | Acta Materialia |
| Volume | 44 |
| Issue number | 3 |
| DOIs | |
| State | Published - Mar 1996 |
Funding
Acknowledgements-This research was supported by the Materials Processing Center at MIT. CMB and DCD gratefully acknowledge the support of the U.S. Army, in the form of a graduate fellowship, and of AMAX, in the form of an endowed chair at MIT, respectively. The authors also express their appreciation to Dynamet Technology Inc. (Burlington, MA) for providing billets, to Mr P. Zwigl from MIT for performing the two superplastic tests to fracture, to Professor A. S. Argon from MIT for use of experimental facilities and to Dr B. Derby from the University of Oxford for helpful discussions.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Ceramics and Composites
- Polymers and Plastics
- Metals and Alloys